Joint for fluid transport lines for medical use

ABSTRACT

The joint ( 36 ) comprises a tubular body ( 37 ) having two connecting zones ( 38, 39 ) each connected by an end to a tubular element ( 40 ) of a fluid transport line, giving continuity to passage of fluid. The tubular body is made of a mixture of an electrically-conductive material such as PVC, with carbon black to give it electrical conductivity. The joint has an internal surface ( 41 ) which is destined to come into contact with the transported fluid, and an external surface which is destined to have a grounded galvanic contact. The joint is inserted in the discharge fluid drainage line of a dialyzer filter, in an apparatus for intensive treatment of acute renal insufficiency, for eliminating ECG artefacts due to functioning of peristaltic pumps in the apparatus.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Italian Application No. M02003 A000165, filed on Jun. 4, 2003, and claims the benefit of U.S.Provisional Application No. 60/511,327, filed on Oct. 16, 2003.

BACKGROUND OF THE INVENTION

The invention relates to a joint for fluid transport lines for medicaluse, to a fluid transport line comprising the joint, to an infusiondevice comprising the line, to a circuit for extracorporeal bloodtreatment comprising the line, to a machine for extracorporeal bloodtreatment which is operatively associable to the circuit, and to anapparatus for extracorporeal treatment of blood comprising the machineand the circuit.

Specifically, though not exclusively, the invention can be usefullyapplied in the field of intensive treatment of acute renalinsufficiency.

In the prior art, renal insufficiency, both chronic and acute, istreated by extracorporeal dialytic treatment, in which blood is removedfrom the patient through a withdrawal line (arterial line) of anextracorporeal circuit; is sent to a first chamber (blood chamber) of adevice for extracorporeal blood treatment (dialyzer or dialyzer filter,or artificial kidney), and is returned to the patient through a returnline (venous line) of the extracorporeal circuit.

The treatment device comprises a second chamber (dialysis chamber) whichis separated from the first by a semi-permeable membrane. The secondchamber has an outlet, fluidly connected to a drainage line for adischarge fluid, and generally also has an inlet, fluidly connected to asupply line of a fresh dialysis fluid.

In some treatments, especially in intensive therapy for treatment ofacute renal insufficiency, one or more infusion lines can be provided,in particular a first infusion line, for supply of a first infusionfluid into the blood withdrawal line upstream of the dialyzer filter(pre-infusion), and a second infusion line, for supply of a secondinfusion fluid into the blood return line, downstream of the dialyzerfilter (post-infusion).

To set up the treatment, the extracorporeal circuit is associated to adialysis machine, which comprises at least one blood pump, in general aperistaltic pump, which is predisposed on the withdrawal line and is forthe circulation of the blood. Usually the machine also comprises variousother pumps, also usually peristaltic, for the circulation of thevarious fluids which flow in the other fluid transport lines: a drainagepump for circulating the discharge fluid along the drainage line; a pumpfor circulation of the fresh dialysis fluid along the supply line to thesecond chamber of the dialyzer filter; and an infusion pump for eachinfusion line.

Normally, during the course of extracorporeal treatment, some of thepatient's physiological parameters are monitored, in particular it isusual to perform the patient's ECG.

One of the problems encountered during a dialysis treatment, especiallyin cases of intensive therapy, is that the rotation of the peristalticpumps, in particular the blood pump, causes disturbances (known asartefacts) in the ECG.

This interference problem in the ECG is found both in complex apparatus,such as a dialysis machine for intensive treatment, as well as in moresimple apparatus, such as an infusion device comprising an infusion linewith a peristaltic pump.

The alteration in the ECG recording can lead to an indistinguishabletracing, or can cause distortions that might be wrongly interpreted andconfused with signs of cardiac anomalies.

SUMMARY OF THE INVENTION

A main aim of the present invention is to provide a solution to theabove-described problem existing in the prior art.

A further aim of the invention is to realize a fluid transport line thatcan be incorporable in a circuit for extracorporeal circulation of bloodand/or medical fluids, thanks to which it is possible to eliminate ECGinterference that can be traced to the operation of the machineassociated to the circuit and which comprises means for circulation ofthe fluid in the circuit itself.

A further aim of the invention is to make available a machine forextracorporeal blood treatment, to which an extracorporeal circuit isoperatively associable and which includes the above-cited fluidtransport line, the functioning of which does not cause disturbances tothe patient's ECG.

A further aim of the invention is to provide an infusion device, inwhich a medical infusion liquid is placed in circulation along aninfusion line by a pump, thanks to which device it is possible toeliminate interferences which disturb the ECG and which are due to theoperation of the pump.

An advantage of the invention is that it offers a simple and economicalsolution to the above-described problem of ECG artefacts caused by theoperation of an apparatus for extracorporeal blood treatment.

A further advantage is that the invention realizes an apparatus forextracorporeal blood treatment which eliminates ECG artefacts and whichat the same time responds to the necessary requisites of electricalinsulation, thus eliminating any risks involving the patient'swell-being.

A further advantage of the invention is that it provides a solutionwhich does not lead to any problems relating to bio-compatibility.

A still further advantage of the invention is that it provides a fluidtransport line, simple and economical to manufacture, which is easilyproduced using known production processes.

These aims and advantages and more besides are all attained by thepresent invention, as it is characterized in one or more of the appendedclaims.

Further characteristics and advantages of the invention will betteremerge from the detailed description of at least one preferred butnon-exclusive embodiment of the invention, made herein below withreference to the accompanying figures of the drawings, which are givenby way of example and which are non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The description will be made with reference to the accompanying figuresof the drawings, provided by way of non-limiting example, and in which:

FIG. 1 is a diagram of a hydraulic circuit usable in a machine forintensive treatment according to the invention;

FIG. 2 is a longitudinal section of a joint for a fluid transport linerealized according to the invention;

FIG. 3 shows the joint of FIG. 2 applied to a fluid transport line;

FIG. 4 is a second embodiment of a joint according to the presentinvention;

FIG. 5 is the joint of FIG. 4 applied to a fluid transport line;

FIG. 6 is a support element which is applicable to a front surface of adialysis machine, and is provided for removable fastening of the jointof FIG. 2 or 4;

FIG. 7 shows the support element of FIG. 6 applied to the front surfaceof a dialysis machine;

FIG. 8 shows section VIII-VIII of FIG. 7;

FIG. 9 is a block diagram of the grounding of an extracorporeal circuitaccording to the present invention;

FIG. 10 is a more detailed version of the electrical diagram of FIG. 9;

FIG. 11 is a recording of an electrocardiograph applied to a dialysisapparatus during laboratory tests, where the invention is not applied;

FIG. 12 is an ECG recording applied to the same apparatus as in FIG. 11,where the invention is applied;

FIG. 13 compares two ECG recordings, taken during laboratory tests; inthe first the conductive joint is not earthed, while in the second it isgrounded with the interpositioning of a suitable safety groundingresistance;

FIG. 14 is a diagram of an infusion device made according to the presentinvention.

DETAILED DESCRIPTION

With reference to FIG. 1, the number 1 denotes an apparatus forextracorporeal treatment of blood, in particular a dialysis machine forintensive treatment.

A blood circuit 2 removes the blood from a patient, through a vascularaccess of known type and not illustrated, and, via at least onewithdrawal line (inlet line or arterial line) 2 a transports the blood,for example with continuous flow, to a blood treatment device 3 (orfiltration unit, or dialyzer filter, or artificial kidney).

The blood crosses a first chamber (or blood chamber) of the bloodtreatment device 3 and, via a return line (or outlet line, or venousline) 2 b, the treated blood is returned to the internal vascular systemof the patient.

The withdrawal line 2 a is connected, immediately downstream of theblood withdrawal zone, to an auxiliary, pre-infusion line 4.

A source of secondary fluid 5 (for example a container or bag), suppliesthe pre-infusion line 4. The apparatus comprises means for moving thefluid, in the illustrated example constituted by an auxiliarypre-infusion pump 6 (for example a peristaltic pump), which means formoving the fluid control the flow of secondary fluid injected directlyinto the blood via the pre-infusion line 4.

The source of secondary fluid 5 can supply a suitable biological fluidto effect a pre-infusion, but can also supply an anti-coagulant.

The blood flows, in a blood circulation direction 7, from the withdrawalline 2 a towards the filtration unit, and from the filtration unit flowvia the return line 2 b back to the patient.

A blood pressure sensor 8 is predisposed immediately downstream of theauxiliary pre-infusion line 4.

The apparatus comprises means for moving fluid, i.e. in the particularcase at least one blood pump 9 for control and management of the bloodflow in the blood circuit 2. The blood pump 9 is generally peristaltic.

A device 10 for administering an anti-coagulant, for example a syringecontaining appropriate doses of heparin, operates on the withdrawal line2 a downstream of the blood pump 9.

The blood passes a further pressure sensor 11 which monitors the correctflow into the blood circuit 2.

Then the blood enters the blood chamber of the treatment device 3,where, through a semi-permeable membrane, the desired substance,molecular and fluidic exchanges occur.

The treated blood, outletting from the treatment device 3, enters thereturn line 2 b, crossing first a gas separator device (generally air)12, predisposed to stop and expel any gassy substances or air bubblespresent in the blood. The separator device 12 is operatively associatedwith a pressure sensor, of known type and not illustrated, forcontrolling the pressure in the return line 2 b.

The treated blood outletting from the separator device 12 then crossesan air bubble sensor 13 which checks for absence of these dangerousformations internally of the treated blood.

Immediately downstream of the air bubble sensor 13 an intercept element14 is located, the function of which is to block, during any alarms, theblood flow towards the patient.

Downstream of the intercept element 14 the treated blood is returned tothe patient undergoing therapy.

A fluid circuit 15 is provided with at least one supply line 15 a of atreatment fluid (fresh dialysis fluid), which enters a second chamber(dialysis chamber) of the treatment device 3, and a drainage line 15 boutletting from the second chamber 3 of the device.

At least one source of treatment fluid 16 is connected to the supplyline 15 a of the fluid circuit 15 (the source of the treatment fluid 16can be constituted, for example, by at least one bag containing adialysis liquid).

The apparatus 1 comprises means for moving the fluid along the supplyline 15 a, including at least one supply pump 17 (in the illustratedembodiment a peristaltic pump), for controlling the flow of thetreatment fluid coming from the source 16 and for defining a directionof circulation 18.

Downstream of the supply pump 17, along the circulation direction 18,there is a split 19 which divides the fluid circuit 15 into an injectionbranch 20 and an infusion branch 21. In particular the infusion branch21 is connected to the return branch 2 b of the blood circuit 2.

The infusion branch 21 enables a post-infusion directly into the bloodcircuit 2, using the treatment fluid coming from the source 16.

The injection branch 20 takes the treatment fluid directly to an inletof the second chamber of the treatment device 3.

A selector switch 22 is predisposed in proximity of the split 19, and isfor determining the percentage quantities of treatment fluid flow intothe infusion branch 21 and into the injection branch 20. The selectorswitch 22, for example a cam switch or clamp switch, can assume at leasta first operative configuration, in which the fluid is allowed to passinto the injection branch 20, and prevents passage into the infusionbranch 21, and a second operative configuration, in which it allowspassage into the infusion branch 21 and prevents passage into theinjection branch 20. The selector switch 22 can modulate the quantitiesof fluid contemporaneously crossing one and the other branches 20 and21, and can determine, including by programming, the changes in thequantities of fluids which flow in one branch or the other according topredetermined times and treatments.

The treatment fluid flowing in the injection branch 20 enters the secondchamber (dialysis chamber) of the treatment device 3, which secondchamber is separated from the first chamber (blood chamber) by thesemi-permeable membrane which, as has already been mentioned, enablesthe correct substance exchanges between the blood and treatment fluid.

The fluid outletting from the second chamber of the treatment device 3,i.e. the discharge fluid, is transported by the drainage line 15 b, alsoknown as the effluent line.

A pressure sensor 23 is predisposed for controlling the functioning ofthe drainage line 15 b.

Downstream of the pressure sensor 23 are located means for moving thefluid, for example a drainage pump 24, generally a peristaltic pump,able to control the flow in the drainage line 15 b of the fluid circuit15.

The discharge fluid crosses a blood leak detector 25 and is eliminatedor directed into a container 26 for discharge fluid.

The apparatus comprises at least one further infusion line 27 whichremoves an infusion fluid from at least one auxiliary source 28 and,using means for moving fluid, usually a peristaltic infusion pump 29which controls the flow, sends the fluid directly to the blood circuit 2return line 2 b. The infusion liquid can be introduced, as in theillustrated embodiment, directly into the gas separator device 12.

The infusion branch 21 of the fluid circuit 15 and the infusion line 27are provided with a common end tract 30 for injection into the bloodcircuit 2. This end tract 30 is located downstream of the infusion pump29 with respect to an infusion direction 14, and terminates directly inthe separator device 12.

The infusion line 27 comprises at least one pre-infusion branch 32connected to the withdrawal line 2 a of the blood circuit 2. In moredetail, downstream of the infusion pump 29 with respect to the infusiondirection 31, there is a split 33 which divides the infusion line 27into the pre-infusion branch 32 and a post-infusion branch 34.

The pre-infusion branch 32 transports the infusion fluid, taken from thecontainer 28, towards the withdrawal line 2 a of the blood circuit 2,downstream of the blood pump 9 with respect to the circulation direction7.

The post-infusion line 34 is directly connected to the common end tract30.

The infusion line 27 is provided with a selector switch 35, predisposedin proximity of the split 33, for determining the percentage quantity ofthe flow of liquid to be sent into the post-infusion branch 34 and thepre-infusion branch 32. The selector switch 35 can assume at least afirst operative configuration, in which it allows passage of fluid intothe pre-infusion branch 32 and prevents passage of fluid into thepost-infusion branch 34, and at least a second operative configuration,in which it allows passage of fluid into the post-infusion branch 34 andprevents passage of fluid into the pre-infusion branch 32. The switch 35can establish the percentage of fluid which must pass into each of thetwo branches 32 and 34, and can if necessary vary the times according tothe treatments to be performed.

The apparatus 1 comprises a disposable part, usable in general for asingle treatment, and a fixed part, which is used a number of times forvarious treatments on various patients. The fixed part is in effect themachine for extracorporeal blood treatment. The machine comprises, ingeneral, a machine body which usually bears, on a front surface thereof,the various peristaltic pumps 6, 9, 17, 24 and 29, and also the varioussensors, denoted by 8, 11, 13, 23 and 25, and the means for controllingflow, denoted by 14, 22 and 35, and an interfacing system with theoperator, which generally comprises a display for entering and readingdata.

The machine body also bears, internally, all of the electronic controlcircuitry, including a machine command unit.

The disposable part comprises the treatment device 3 and the bloodcircuit 2; in the illustrated embodiment, in which the apparatus servesto perform dialysis treatment of the intensive kind, the disposable partalso comprises the dialysis circuit 15.

Substantially the machine integrates all of the instrumentation andapparatus destined to be used more than once, in various treatments, onone or more patients.

The disposable parts, destined to be used only once for each treatmentto be performed on a patient, are borne on an integrated module, ofknown type and not illustrated, of the single-use type, applicabledirectly on the machine body.

The operation of the apparatus 1 includes a preliminary part, in whichthe disposable part is associated to the front surface of the machinebody. During this phase the hydraulic circuit (blood circuit 2 anddialysis circuit 15) and the blood treatment circuit 3 are mounted onthe machine in such a way that: the various peristaltic pumps engage thepredisposed tracts of tubing (pump segments), which are generallyU-shaped; all of the sensors are correctly engaged; and the containersof the various fluids are fluidly coupled to the respective fluidtransport lines.

After the blood circuit 2 has been connected, in a known way, to avascular access of a patient, the blood pump 9 is started up, whichstarts circulation of the blood in the circuit.

Thereafter, according to the type of treatment to be performed, themachine for extracorporeal blood treatment is automatically started upand controlled by the command unit.

The apparatus for extracorporeal blood treatment described above is ableto perform treatments, in particular intensive treatments, each of whichcomprises one or more of the following treatments, with predeterminablesequences: pure ultrafiltration, haemofiltration, haemodialysis,haemodiafiltration, plasma exchange.

In FIG. 1, 36 denotes a joint for fluid transport lines for medical use,which is made according to the object of the invention. The joint 36 ispredisposed along the drainage line 15 b immediately downstream of theblood treatment device 3, that is, just after the outlet from the secondchamber of the device 3 and before the drainage pump 24. In theillustrated embodiment, the joint 36 is located between the pressuresensor 23 and the drainage pump 24. This joint 36 will be described inmore detail herein below.

The joint 36 is illustrated, in a first embodiment, in FIG. 2. In FIG.3, the joint 36 is coupled to the drainage line 15 b.

The joint 36 comprises a tubular body 37, substantially a sleeve-shape,having a cylindrical lateral external side and at two opposite ends twoconnecting zones 38 and 39, each of which, has a cylindrical internallateral surface for connecting with an end zone of a usual tubularelement 40 of a fluid transport line for medical use. The connectiongives continuity to fluid passage.

Each tubular element 40 is a flexible elongate body, with elasticallydeformable walls, made of a dielectric plastic material, generally athermoplastic resin, such as for example bio-compatible plasticized PVC.

The joint 36 is made in a single piece with a relatively smalllongitudinal extension having more rigid walls than the tubular elements40.

In the illustrated example the joint 36 is made of a composite materialincluding a mix of plastic material, generally a thermoplastic resin(for example the same material as the tubular elements 40, in thisembodiment bio-compatible plasticized PVC), with at least one additiveto give it electrical conductivity.

The combination of the above-mentioned additive with the thermoplasticresins, already dielectric, in suitable and known formulas, leads toobtaining a conductive material, though provided with relatively highelectrical resistance.

The additive can be, for example, conductive carbon black, or anotherknown product which, mixed with a thermoplastic resin, transforms thelatter from being an insulator to being a conductor.

In the illustrated embodiment, the material, obtained from a mixture ofa plastic material and a conductor additive, can be extruded by usualprocesses and apparatus used for PVC.

In more detail, in the illustrated embodiment, the selected material forthe conductive joint 36 is CABELEC® 3895, constituted by a compoundincluding carbon black, plasticized PVC, stabilizer and lubricant.

The two connecting zones 38 and 39 of the joint are designed andstructured to join the two tubular elements 40 solidly, one to another(even though axially distanced one from another), giving continuity tofluid passage. The two tubular elements 40, joined together by the joint36, form a single conduit for the passage of a fluid.

The tubular body 37, made in a single piece, is produced by a plasticmaterial pressing process.

The tubular body 37 is internally provided with at least one internalsurface 41, destined to come into contact with the transported fluid,situated in an intermediate axial zone of the tubular body 37 comprisedbetween the two end connecting zones 38 and 39.

The external surface of the tubular body 37 is destined to contactelectrically with an element which is external of the fluid transportline, with the result that, via for example a grounded connection, theelectrical currents present in the transported fluid transported in thefluid transport line can be dissipated. The external element,illustrated in figures from 6 to 8, will be better described hereinbelow.

The tubular conductive joint 36, has a greater electrical conductivitythan the tubular elements 40 which are reciprocally joined by the joint36. The material of the tubular body 37 is, as has been mentioned, isbased on a thermoplastic material, which in itself is dielectric, andwhich is made electrically conductive thanks to the addition, in thebody of the plastic material, of carbon black or another suitableadditive for obtaining electrical conductivity.

The joint 36 can therefore be considered an electrically conductiveelement, differently to the plastic tubular elements 40, which can beconsidered electric insulators.

The conductive joint 36 can be considered a high-resistanceelectrically-conductive element.

To achieve the desired aim, i.e. to considerably reduce or eveneliminate disturbance of the ECG caused by electrostatic chargesgenerated by the operation of peristaltic pumps, in particular the bloodpump 9, the electrical impedance between the internal surface and theexternal surface of the tubular body 37 can vary within a range between40 KΩ and 10 MΩ. As will be more fully explained herein below, asubstantial elimination of electrocardiograph disturbances has beenverified, with the ECG connected up to a patient being subjected toextracorporeal treatment, using, in the apparatus, a conductive joint 36having an electrical impedance variable between 200 KΩ and 2 MΩ.

The material and conformation of the joint 36 simply and economicallyobtain a good, stable, resistant and well-sealed joint, between thejoint 36 and the tubular elements 40 which it joins. The joint union,permanently stable and unbreakable, can be obtained, during assembly, bya process of known type and already in use, for example, for solidconnections by gluing of PVC tubes for medical products havingcorresponding plastic connectors. The procedure involves insertion ofthe end zones of the tubular elements 40 inside the connecting zones 38and 39 of the joint 36, with a preliminary spreading on at least one ofthe coupling surfaces of a certain amount of a suitable glue, forexample a cyclo-hexanone-based glue.

In a second embodiment, illustrated in FIG. 4, the conductive joint 36′is constituted by a tubular body 37′, made in a single piece, whichinternally comprises at least one first axial stop element 42,operatively associated to an end zone of a first tubular element 40′,for limiting an axial insertion of the first tubular element within thetubular body.

In the illustrated embodiment, the tubular body 37′ internally comprisesa second axial stop element 43, axially distanced from the first axialstop element 42, and operatively associated to an end zone of the secondtubular element 40″, for limiting an axial insertion of the secondtubular element inside the tubular body 37′, in an opposite directionwith respect to the axial insertion of the first tubular element 40′.

The tubular body 37′ has an intermediate zone 41′ comprised axiallybetween the two end connecting zones 38′ and 39′, the internal diameterof which is smaller than the internal diameter of the connecting zones.The intermediate zone 41′, with a smaller diameter, offers aninwardly-directed annular recess, axially delimited by two abutments,which form the stop elements 42 and 43 which limit insertion of the endzones of the tubular elements 40′ and 40″. The elements 42 and 43 havethe function of preventing total covering of the internal surface of thetubular body 37′ by the tubular elements 40′ and 40″, so that a freeintermediate zone 41′ on the internal surface remains free, i.e. notcovered by the end zones of the tubular elements 40′ and 40″, and indirect contact with the fluid which flows along the fluid transportline. This direct contact allows for dispersion to the outside of anyelectrostatic charges in the fluid.

The drainage line 15 b of the apparatus 1 is an example of a fluidtransport line, for medical use, made according to the invention.

The fluid transport line comprises at least a first part and a secondpart, both in contact with the transported fluid, in which the secondpart is made of a material having a greater electrical conductivity thanthe material the first part is made of. The second part of the line cancomprise, as in the embodiment described herein, a conductive joint 36or 36′ like those first described, while the first part can comprise thetubular elements 40, 40′, 40″ described above.

The second part of line is also predisposed for galvanic connection toan element which is external of the line, as will be better explainedherein below.

The conductive second part of the line exhibits at least one internalsurface destined to contact with the transported fluid, and at least oneexternal surface predisposed to be associated, in electrical contact,with a support element which is external of the line.

The first part is made of a thermoplastic material which is elasticallydeformable and dielectric, while the second part is made of a materialcomposed of a mix of thermoplastic, dielectric material with theaddition of at least one additive which gives the mixture a certainelectrical conductivity.

The additive also has the property of giving greater rigidity to themixture.

The second part of the electrically conductive line is situated, withreference to the fluid transport direction, upstream of a pump segmentof the line. The pump segment is a tract of line, normally U-shaped andelastically deformable, which is operatively associated to anormally-peristaltic pump, for circulation of the transported fluid.

The second part of electrically-conductive line can be located, in otherembodiments which are not illustrated, in any other point of thehydraulic circuit of FIG. 1, either in the fluid circuit 15 (or dialysiscircuit) or in the blood circuit 2.

The location on the drainage line 15 b, immediately downstream of thetreatment device 3, has the advantage of ensuring an efficientelectrical connection between the second part of line (the joint 36) andthe blood circuit 2, without resorting to direct contact between theblood and the second part of electrically-conductive line.

It has been found that the treatment device 3, or dialyzer filter, doesnot constitute a barrier to electrical communication between the bloodcircuit 2 and the fluid circuit 15.

This advantage can be found also in hydraulic circuits which aredifferent from the one illustrated in FIG. 1: in particular, the use ofthe second conductive part of line is effective also in simplifiedhydraulic circuits, such as for example a circuit for haemodiafiltrationsuch as the one illustrated in FIG. 1, but lacking the branches 21 and34, or a suitable circuit for effecting only haemofiltration, or acircuit suitable only for haemodialysis, or a circuit suitable only forpure ultrafiltration.

An apparatus for extracorporeal blood treatment, predisposed forcooperating with one of the above-cited hydraulic circuits, comprises atleast one support element 44 predisposed to receive, with a mechanicalengagement and in electrical contact, the above-mentioned second,electrically-conductive part of line (joint 36 or 36′).

The support element 44 is solidly connected to a front panel 45 of themachine for extracorporeal blood treatment. An embodiment of thissupport element 44 is illustrated in FIG. 6, while FIGS. 7 and 8 showthe same support element 44 applied to the front panel 45 of the machine(in FIG. 7 the blood leak detector 25 can also be seen, located by theside of the support element 44).

The support element 44 comprises at least one electrically-conductivefirst part 46, made, for example, of metal, fixed to the front panel 45of the machine by, for example, a screw connection 47. The conductivefirst part 46 can comprise a threaded stalk 48 for the screw connectionwith the front panel 45.

The support element 44 further comprises a second part 49, alsodielectric and made of a plastic material, provided with a grippingorgan 49 a for removably fixing the fluid transport line to theconductive second part (the joint). The first and second parts 46 and 49of the support element are solidly constrained one to another, forexample by a screw connection (not illustrated).

The gripping organ 49 a comprises, for example, a fastening, in theguise of an elastically deformable hook, which affords a seating inwhich the conductive joint 36 or 36′ can be inserted and held tight inposition. The joint 36 or 36′ can be inserted and and removed manuallyfrom the seating.

The apparatus 1 further comprises a galvanic connection 50 whichconnects the support element 44 with an external mass, for externaldissipation of any electrical charges present in the fluids, corporealand/or medical, transported in the extracorporeal hydraulic circuit. Thegalvanic connection 50 terminates in the conductive first part 46 of thesupport element 44. In the illustrated embodiment the galvanicconnection 50 is a true and proper earth for the joint 36, comprising atleast one electrical earthing cable which connects the conductive firstpart of the support element, which is in contact with theabove-mentioned conductive second part of line (joint 36 or 36′), withthe machine body, which machine body is in turn normally provided withits own grounding.

The galvanic connection 50 also comprises at least one safety electricalimpedance 51, of a predetermined entity, predisposed along the groundingcable between the support element 44 and the machine body. This safetyimpedance 51 guarantees the machine's electrical insulation, as requiredby the standards, together with the impedance value of the conductivejoint 36 or 36′. The entity of the electrical impedance 51 can be, forexample, above about 0.1 MΩ. It has been found that an efficientelimination of ECG artefacts (caused by the action of the peristalticpumps) is also achieved with a safety impedance 51 of above about 1.0MΩ.

Alternatively to the use of a single impedance 51 of about 1.0 MΩ, aplurality of electrical impedances, of predetermined entities (forexample each not below about 2.0 MΩ), could be predisposed in parallelalong the galvanic connection, with the aim of reducing the powerdissipated.

The galvanic connection to earth can comprise, for example, anelectronic board having: one or more impedances having predefinedcharacteristics, at least a first contact for connecting to theconductive part 46 of the support element, and at least a second contactfor connecting to the earthing cable.

FIG. 9 shows a block diagram of the electrical earthing system of thehydraulic circuit of the apparatus 1. 52 denotes, in its entirety, thedisposable part of the dialysis apparatus, which is provided with atleast one conductive element in contact with at least one fluid which istransported along at least one tract of the hydraulic circuit of theapparatus. 53 denotes, in its entirety, the fixed part of the dialysisapparatus which comprises the support element 44, which, as mentioned,functions as a mechanical fastening and as an electrical contact for theconductive element of the disposable part. 54 denotes the machine body54 of the machine, which is equipped with it own galvanic earthingconnection 55, of known type. 56 denotes the electrical connectionswhich connect up the various above-mentioned elements among themselves.

FIG. 10 is a more detailed electrical diagram: 57 denotes the electricsupply, 58 the machine command unit, 59 the operator interface display,60 the entirety of the peristaltic pumps for circulation of the variousfluids (corporeal and medical), 61 the entirety of the control organsfor regulation of the various fluid transport lines (clamps, valves,selectors etc.), 62 the totality of the sensors (pressure, blood,air-bubble, any fluid-container weighing sensors there might be, and soon).

During the phase of readying the apparatus for operation, in which thedisposable part is associated to the machine, the conductive joint 36 or36′ is pressure-fitted, simply and manually, in the seating constitutedby the elastic fastening of the support element 44.

This simple operation makes possible the galvanic grounding connectionof the discharge fluid circulating in the drainage line 15 b of thedialysis fluid circuit.

Figures from 11 to 13 show the results of some laboratory testsperformed to evaluate the effectiveness of the solution proposed ineliminating the ECG artefacts due to the rotation of the peristalticpumps.

During the tests an apparatus comprising a machine for dialysistreatment was used, such as the one illustrated in FIG. 1, fitted with adisposable integrated module which includes both the blood circuit andthe dialysis circuit, and also the dialyzer filter. The dialysis circuitused in the tests is the fluid circuit 15 of FIG. 1, minus branches 21and 34.

A saline solution (9 g/l) was circulated in the blood circuit, takenfrom a container and returned to the same container; blood pump flowrate was fixed at 180 ml/min.

Four steel electrodes were immersed in the container, connected by aresistance to terminals L (47 KΩ), R (380 KΩ), F (47 KΩ) and N (47 KΩ)of an electrocardiograph. Terminal L was unbalanced by introducing,after the resistance, a 400 pF, condenser towards the ground. The slightunbalance of the impedance of electrode L transforms the common modevoltage produced by the rotation of the pump into a differential signalwhich is recorded by the ECG on I.

Before performing the test, the conductivity of the conductive joint 36was measured. For this purpose, the joint was filled with salinesolution (9 g/l) and the electric resistance between the externalsurface of the joint and the liquid inside was measured. The joint usedin the tests had a resistance which varied between 200 KΩ and 2 MΩ.

FIG. 11, which shows the recording obtained with the conductive jointnot grounded, evidences the disturbance produced by the pump rotation(paper speed 25 mm/sec, disturbance synchronous with movement of pump atabout 6 c/s). There was disturbance on all cutouts with the exception ofno. III, where disturbance is rejected and the impedances of therelative electrodes were exactly balanced. The automatic interpretationof the tracing gives abnormal ECG with atrial fibrillation, abnormalright axial deviation, unspecific intraventricular blockage.

FIG. 12 shows the ECG recording of the same test after the conductivejoint, positioned on the effluent line immediately downstream of thedialyzer filter, has been galvanically connected to ground. The groundconnection consists in connecting the joint by an electric cable to themachine body which in turn is grounded through the supply circuit.

By comparing the recording of FIG. 12 with that of FIG. 11, the groundconnection considerably attenuates the disturbance produced by themovement of the blood pump. The automatic response provided by the ECGcomputer gives atypical ECG (as these were in vitro tests) and declaresitself unable to give a complete interpretation.

FIG. 13 compares two test recordings. The top trace relates to asituation in which the conductive joint was not grounded: the automaticinterpretation gives abnormal ECG with atrial flutter, epicardiaclesions, possibility of frontal infarct. The bottom trace relates to asituation in which the joint is grounded and in which, along theelectric connecting cable between the joint and the body of the machine,a 1.2 MΩ resistance has been positioned. The automatic responsedescribes an atypical ECG, but none of the negative interpretationsgiven for the top tract.

The test result is a demonstration of the elimination of the ECGinterference, even when a resistance is put in the ground connectionwhich resistance is sufficient to conserve the requisite of electricalinsulation of the machine.

The fluid transport line for medical use, comprising the conductivejoint 36 or 36′, as above described, can be used in the fields varioustypologies of medical apparatus where ECG interference is a problem. Inthis specific case the description relates to an apparatus for intensivetreatment of acute renal insufficiency: it would be possible however touse the invention in other medical apparatus, such as for exampledialysis apparatus for chronic renal insufficiency.

A further example is now described in more detail, of application of theconductive joint in an infusion device, with reference to FIG. 14.

The device comprises:

-   -   a source 63 of an infusion liquid;    -   an infusion line 64 having a first end, an inlet 64 a, connected        to the source 63 and a second end, an outlet 64 b, which is        placed in fluid communication, either directly or indirectly,        with the vascular system of a patient;    -   an infusion pump 65, for example a peristaltic pump, operatively        associated to the infusion line 64 for circulating the infusion        liquid;    -   a conductive joint 66, made like the joint 36 or 36′,        predisposed along the infusion line 64 upstream of the pump 65;    -   a galvanic connection 67 for connecting the conductive joint 66        with an external mass (for example the ground).

The device can further comprises a safety impedance 68, predisposedalong the galvanic connection 67, having the function of guaranteeingthat the electrical insulation for the patient undergoing the infusiontreatment is in conformity with existing safety standards, and amechanical fastening and electrical contact element, denoted by 69, towhich the conductive joint 66 is applied, for example removably.

The infusion line 64 can be connected, directly to a vascular access ofthe patient, or indirectly to the patient, via an extracorporealcircuit.

In the case of an infusion device too, the material the conductive joint66 is made of is a polymer which has been made conductive thanks toaddition and mixing of carbon black or another known additive. As can beobserved, in this case too the conductive joint 66 is located upstreamof the peristaltic pump 65, with reference to the infusion fluidcirculation direction.

The electrical contact element 69 destined to engage with the conductivejoint 66, which can be once more, for example, an elastic fastening, canbe solidly constrained to the pump body of the peristaltic pump 65.

The particular location, before the fluid circulation pump, of theconductive element guarantees reciprocal contact, constantly and in alloperative situations, between the transported fluid and the conductiveelement.

In the illustrated embodiments the transport fluid which is galvanicallyconnected to the outside is, in the first case (FIG. 1) the dischargefluid in the drainage line of a dialyzer filter, and in the second case(FIG. 14) the infusion fluid circulating along an infusion line, simpleor cooperating with an extracorporeal blood circuit. Other transportfluids could, however, be galvanically connected to the outside, such asfor example blood, circulating in the withdrawal line or the return lineof an extracorporeal circuit, or fresh dialyzing fluid, circulating inthe supply line of the dialysis chamber of a dialyzer filter, or thepre-infusion or post-infusion liquid of a dialysis circuit.

1. A circuit for extracorporeal treatment of blood, comprising: at leastone blood withdrawal line configured to supply blood removed from apatient to at least a first chamber of a blood treatment device; atleast one blood return line configured to return the blood to thepatient after the blood exits said first chamber of the blood treatmentdevice; and at least one drainage line for draining a discharge fluid,said discharge fluid exiting a second chamber of the blood treatmentdevice, said second chamber being separated from said first chamber by asemi-permeable membrane, said drainage line comprising at least a firstpart, and a second part, said first and second parts being configured tocontact the discharge fluid, said second part including a materialhaving an electrical conductivity greater than an electricalconductivity of a material forming said first part, said second partbeing configured to provide a galvanic connection with an elementexternal to the drainage line, said second part comprises a joint havinga tubular body with a first end having a first connecting zone and asecond end having a second connecting zone, said first and second endsbeing opposite one another, said tubular body including an electricallyconductive material, said first part including a first tubular elementand a second tubular element, said first and second tubular elementsbeing coupled to said tubular body at said first and second connectingzones, said joint comprises at least one internal surface configured tocontact the discharge fluid, and at least one external surfaceconfigured to electrically contact an element, said element beingexternal to the drainage line, in order to dissipate any electriccharges present in the discharge fluid, the joint further having anelectrical resistance between said internal surface and said externalsurface, said electrical resistance being comprised between 40 KΩ and 10MΩ.
 2. The circuit of claim 1, wherein said drainage line furthercomprises a pump segment configured to be operatively coupled to a pumpfor circulation of the drainage fluid along said drainage line, andwherein said second part is located between an inlet end of saiddrainage line, and said pump segment, said inlet end being configured tobe connected to an outlet of said second chamber.
 3. The circuit ofclaim 2, wherein said second part is located immediately downstream ofsaid inlet end of the drainage line.
 4. The circuit of claim 1, whereinsaid second part further comprises at least one internal surfaceconfigured to contact the discharge fluid, said second part having atleast one external surface configured to provide electrical contact witha support element, said support element being external to the drainageline.
 5. The circuit of claim 1, wherein said tubular body includes atleast one plastic material, said plastic material comprising at leastone additive, wherein said additive supplies electric conductivityproperties to said tubular body.
 6. The circuit of claim 5, wherein saidadditive comprises carbon.
 7. The circuit of claim 5, wherein saidplastic material comprises PVC.
 8. The circuit of claim 1, wherein saidelectrical resistance is between 200 KΩ and 2 MΩ.
 9. The circuit ofclaim 1, wherein the material of said first part of the line includes anelastically deformable plastic material, and the material of said secondpart of the line includes a second elastically deformable plasticmaterial, said material of said second part of the line having at leastone additive such that the material of said second part of the line iselectrically conductive.
 10. The circuit of claim 9, wherein saidadditive increases a rigidity of the material of said second part of theline.
 11. The circuit of claim 9, wherein said material of said secondpart of the line is PVC, and said additive is carbon.
 12. The circuit ofclaim 1, wherein said second part is located upstream of a pump segmentof the drainage line, said pump segment being configured to beoperatively associated to a pump for circulation of the drainage fluid.13. The circuit of claim 1, further comprising at least one line forcirculation of a fluid chosen from a group of lines, including: at leastone supply line for supplying an operative fluid to said second chamberof the treatment device; at least a first infusion line for infusion ofa substitution fluid to said blood withdrawal line; and at least asecond infusion line, for infusion of a substitution fluid to said bloodreturn line.
 14. A circuit for extracorporeal treatment of blood,comprising: at least one blood withdrawal line configured to supplyblood removed from a patient to at least a first chamber of a bloodtreatment device; at least one blood return line configured to returnthe blood to the patient after the blood exits said first chamber of theblood treatment device; and at least one drainage line for draining adischarge fluid, said discharge fluid exiting a second chamber of theblood treatment device, said second chamber being separated from saidfirst chamber by a semi-permeable membrane, said drainage linecomprising at least a first part and a second part, said first andsecond parts being configured to contact the discharge fluid, saidsecond part including a material having an electrical conductivitygreater than an electrical conductivity of a material forming said firstpart, said second part being configured to provide a galvanic connectionwith an element external to the drainage line, said second partcomprises a joint having a tubular body with a first end having a firstconnecting zone and a second end having a second connecting zone, saidfirst and second ends being opposite one another, said tubular bodyincluding an electrically conductive material, said first part includinga first tubular element and a second tubular element, said first andsecond tubular elements being coupled to said tubular body at said firstand second connecting zones, said tubular body comprising at least onefirst axial stop element, said at least one first axial stop elementbeing operatively coupled to an end zone of a first tubular element, forlimiting an axial insertion of said first tabular element inside saidtubular body.
 15. The circuit of claim 14, wherein said tubular bodycomprises at least one second axial stop element spaced axially from theat least one first axial stop element, said at least one second axialstop element being operatively associated to an end zone of a secondtubular element, for limiting an axial insertion of said second tubularelement inside said tubular body, the axial insertion of said secondtubular element inside said tubular body being in an opposite directionto an axial insertion of said first tubular element.
 16. The circuit ofclaim 14, wherein said at least one first axial stop element is arrangedinternal to said tubular body.
 17. A circuit of for extracorporealtreatment of blood, comprising: at least one blood withdrawal lineconfigured to supply blood removed from a patient to at least a firstchamber of a blood treatment device; at least one blood return lineconfigured to return the blood to the patient after the blood exits saidfirst chamber of the blood treatment device; and at least one drainageline for draining a discharge fluid, said discharge fluid exiting asecond chamber of the blood treatment device, said second chamber beingseparated from said first chamber by a semi-permeable membrane, saiddrainage line comprising at least a first part and a second part, saidfirst and second parts being configured to contact the discharge fluid,said second part including a material having an electrical conductivitygreater than an electrical conductivity of a material forming said firstpart, said second part being configured to provide a galvanic connectionwith an element external to the drainage line, said second partcomprises a joint having a tubular body with a first end having a firstconnecting zone and a second end having a second connecting zone, saidfirst and second ends being opposite one another, said tubular bodyincluding an electrically conductive material, said first part includinga first tubular element and a second tubular element, said first andsecond tubular elements being coupled to said tubular body at said firstand second connecting zones, said tubular body having a freeintermediate zone not used for connecting, said free intermediate zonebeing axially disposed between said first and second connecting zonesand configured to contact the discharge fluid.
 18. The circuit of claim17, wherein said free intermediate zone has an internal diameter lessthan an internal diameter of said first and second connecting zones. 19.A circuit for extracorporeal treatment of blood, comprising: at leastone blood withdrawal line configured to supply blood removed from apatient to at least a first chamber of a blood treatment device; atleast one blood return line configured to return the blood to thepatient after the blood exits said first chamber of the blood treatmentdevice; and at least one drainage line for draining a discharge fluid,said discharge fluid exiting a second chamber of the blood treatmentdevice, said second chamber being separated from said first chamber by asemi-permeable membrane, said drainage line comprising at least a firstpart and a second part, said first and second parts being configured tocontact the discharge fluid, said second part including a materialhaving an electrical conductivity greater than an electricalconductivity of a material forming said first part, said second partbeing configured to provide a galvanic connection with an elementexternal to the drainage line, said second part comprises a joint havinga tubular body with a first end having a first connecting zone and asecond end having a second connecting zone, said first and second endsbeing opposite one another, said tubular body including an electricallyconductive material, said first part including a first tubular elementand a second tubular element, said first and second tubular elementsbeing coupled to said tubular body at said first and second connectingzones, said tubular body being a single piece.
 20. A circuit forextracorporeal treatment of blood, comprising: at least one bloodwithdrawal line configured to supply blood removed from a patient to atleast a first chamber of a blood treatment device; at least one bloodreturn line configured to return the blood to the patient after theblood exits said first chamber of the blood treatment device; and atleast one drainage line for draining a discharge fluid, said dischargefluid exiting a second chamber of the blood treatment device, saidsecond chamber being separated from said first chamber by asemi-permeable membrane, said drainage line comprising at least a firstpart and a second part, said first and second parts being configured tocontact the discharge fluid, said second part including a materialhaving an electrical conductivity greater than an electricalconductivity of a material forming said first part, said second partbeing configured to provide a galvanic connection with an elementexternal to the drainage line, said second part comprises a joint havinga tubular body with a first end having a first connecting zone and asecond end having a second connecting zone, said first and second endsbeing opposite one another, said tubular body including an electricallyconductive material, said first part including a first tubular elementand a second tubular element, said first and second tubular elementsbeing coupled to said tubular body at said first and second connectingzones, said first and second tubular elements including first and secondend zones, said first and second end zones being inserted inside saidtubular body, said tubular body comprising an axial intermediate zoneprovided between said first and second connecting zones, wherein saidaxial intermediate zone is not covered by said first and second endzones of said first and second tubular elements, said axial intermediatezone being configured to contact the discharge fluid.
 21. The circuit ofclaim 20 wherein said axial intermediate zone has an internal diametersmaller than an external diameter of said first and second end zones ofsaid first and second tubular elements.